Electrons in gases and vacuum

To study a.c. wave forms using a cathode ray oscilloscope

To study a.c. wave forms using a cathode ray oscilloscope In addition to the tube, a cathode ray oscilloscope contains a sweep generator or time-base circuit. When this is switched on it applies a potential difference to the Xplates which builds up uniformly with time to a maximum and then repeats the process at regular intervals. The result …

To study a.c. wave forms using a cathode ray oscilloscope Read More »

The cathode ray oscilloscope

The cathode ray oscilloscope The cathode ray oscilloscope is an instrument used for studying the current and voltage wave forms in various electric circuits. In this connection it is very useful for checking laboratory electric equipment and television and radio receivers. The chief feature of an oscilloscope is the cathode ray tube, which is a vacuum tube containing …

The cathode ray oscilloscope Read More »

Experimental thermionic electron tubes

Experimental thermionic electron tubes Fig. 44.11 shows a thermionic tube designed to show the deflection of moving electrons in an electric field. Its electron gun consists of a cylindrical cathode with a hot metal filament inside to provide a supply of electrons by thermionic emission. The electrons are ac celerated towards a cylindrical anode and emerge as a …

Experimental thermionic electron tubes Read More »

What happens inside an electric discharge tube?

What happens inside an electric discharge tube? We shall now return to the electric discharge tubes described earlier in this chapter. The processes which go on inside these tubes are complex and difficult to investigate, so that physicists hold different views regarding explanations of the various dark spaces, striations and so on. However, all agree that ions …

What happens inside an electric discharge tube? Read More »

The Edison effect. Thermionic emission

The Edison effect. Thermionic emission In 1883, the American scientist and inventor, Thomas Edison, was experimenting with an incandescent electric filament lamp which also contained a small metal plate supported by a wire sealed through the glass. When a battery and galvanometer were connected between the plate and filament he found that a small current flowed through the galvanometer …

The Edison effect. Thermionic emission Read More »

Specific charge

Specific charge The ratio e/m2 mentioned in the previous paragraph is called the specific charge of an electron. Its units are coulmbs/kilometer. Note the use of the word specific which, as we  have seen before in this book, refers to a property of unit mass of something.